In the related art, an imaging apparatus for diagnosis has been widely used for diagnosis of arteriosclerosis, for preoperative diagnosis at the time of intravascular treatment using a high performance catheter such as a balloon catheter or stent, or for checking a result after the surgical operation.
The imaging apparatus for diagnosis can include an intravascular ultrasound (IVUS) diagnostic apparatus and an optical coherence tomography (OCT) diagnostic apparatus, each having different characteristics.
Recently, an imaging apparatus for diagnosis having a combination of the IVUS function and the OCT function has been proposed. Such an imaging apparatus for diagnosis has an imaging core that rotatably accommodates an ultrasound transceiver capable of transmitting or receiving an ultrasound wave and an optical transceiver capable of transmitting or receiving light at a distal end position of the catheter. In the case of such an imaging apparatus for diagnosis having both functions, both a cross-sectional image taking advantage of the IVUS characteristics, that is, a capability of measurement up to a high depth region, and a cross-sectional image taking advantage of the OCT characteristics, that is, a capability of measurement with a high resolution, can be created through a single scanning operation.
However, due to influences of a distance between the ultrasound transceiver and the optical transceiver, installation precisions of the ultrasound transceiver and the optical transceiver, a deviation in the emitting direction, it can be difficult to arrange the IVUS tomographic image obtained by the IVUS function and the OCT tomographic image obtained by the OCT function in the same orientation. In this regard, there is also known a technique of rotating these images until a distance between a landmark of the blood vessel wall in the IVUS tomographic image and a landmark of the blood vessel wall in the OCT tomographic image is minimized (for example, JP-A-2014-180575).
However, in the technique of JP-A-2014-180575, although the orientations of the tomographic images are aligned, a part of the image visualizes a blood vessel wall at a position shifted by one cycle from each other. That is, in one of the images, the shifted part corresponds to the initial part out of the scanning of one revolution constituting one frame of a tomographic image. Meanwhile, in the other image, the shifted part corresponds to the last part out of the scanning of one revolution.